The invention relates to a magnetic device comprising at least one thin layer of a magnetizable material which has an easy axis of magnetization which is substantially normal to the surface of the layer. A propagation pattern of magnetizable material and a detection pattern of magnetoresistive material are provided on said layer. An external magnetic field may be provided as means for propagating magnetic domains in the layer in conjunction with the propagation pattern, and electrical circuitry may be provided as means for detecting magnetic domains in conjunction with the detection pattern.
In such a device which is known from AIP Conference Proceedings No. 24 Magnetism and Magnetic Materials 1974 pages 556-557, the configuration of the pattern of magnetizable material is such that the magnetic domains propagate in response to a rotating magnetic field in the layer. For that purpose the configuration satisfies that of a propagation element for magnetic domains. The configuration of the pattern of magnetoresistive material is such that the detection of the magnetic domains is realized in cooperation with the means for detecting magnetic domains. For that purpose the configuration satisfies that of a detection element for magnetic domains, which means, inter alia that this pattern should be capable of conducting current in connection with the magnetoresistive detection. The two patterns are substantially co-planar and are separated from the layer of magnetizable material by a layer of SiO.sub.2.
In manufacturing the device, two patterns are provided one after the other by means of mask technology. This means that in providing the second pattern the associated mask has to be aligned very accurately with respect to the first pattern. In the article it is stated that this technique has only limited application as the bubble domain sizes decrease toward 1 .mu.m, because of these alignment problems.